Urgent replacement of Hydrogen maser frequency standard for e-MERLIN and VLBI.

e-MERLIN is the UK's national facility for radio astronomy imaging. With 7 telescopes across the UK, linked by a dedicated optical fibre network to a powerful correlattion hub at Jodrell Bank Observatory, the array provides radio imaging at centimetre wavelengths with similar resolution to the optical images produced by the Hubble Space Telescope. When radiop telescopes at JBO are joined with others in Europe and around the world, images at even greater resolution can be produced allowing for example the physical processes near black holes to be studied. The 76-m Lovell Telescope at JBO is still one of the worlds most productive in terms of studying pulsars (spiining neutron stars) and in conjunction with other telescopes acrtoss Europe is searching for the signals of gravitational waves by making the most accurate timing measuremenrs of pulsars. All these observations require a reliable, stable and accurate time and frequency standard in order to coherently combine signals from separate telescopes and to mke the most precise timing measurements. The 'gold standard' frequency standard (or clock)for these measurements is a type of atomic clock known as a hydrogen maser. JBO purchased an H-maser almost 30 years ago when these were first adopted by radio astronomy obsservatories, but this is now well past its expected lifetime and had had to be repaired several times. Its crucial position in our observing system means that we need to replace it now.

Scientific and technical research and development in radio astronomy has a broad impact on society as well as scientific advance in many of the Science Challenges outlined by STFC. e-MERLIN, VLBI and Lovell Telescope research projects will have impact in all four of the key STFC science areas: work on pulsars and gravitational waves allow precise tests of gravity and fundamental physics (STFC Science Challenges C2, D1, D2, D3); searching for fast radio bursts, transients and potential signals from extra-terrestrial intelligence (B3, C4); observations of planet and star-formation probe some of the crucial and poorly understood phases in these processes (B1, A6); studies of galaxy formation and evolution will allow significant advance in understanding how when and where galaxies formed the bulk of their stars (A4, A5) and experiments in cosmic shear and gravitational lensing probe dark matter and dark energy (A3, C4, C5). All these observations require the sensitivity provided by the cryogenic receivers, whose components are requested here.

The wider impact of radio astronomy research is a key part of activities at Jodrell Bank Observatory and the Jodrell Bank Discovery Centre, which now has over 160,000 visitors/year and a dedicated schools programme reaching more than 10,000 pupils/yr. e-MERLIN science and technology form an important part those exhibits and activities and e-MERLIN staff gives talks and presentations at various levels at many events in the Discovery Centre and elsewhere, including music and science festivals attended by up to 20,000 visitors.

Radio astronomy technology developed as part of e-MERLIN and VLBI has had a major impact on the UK participation in the Square Kilometre Array project: the UK leads ths signal and data transport consortium for SKA, based on its experience and expertise from e-MERLIN and e-VLBI. Radio astronomy technology has had a wide impact in general, from the development of low noise amplifiers, large parabolic antennas, algorithms for image processing and medical imaging; wi-fi technology was developed by radio astronomers in Australia, following the experiments with dedicated hardware for radio astronomy signal processing.